Carborundum—known scientifically as Silicon Carbide (SiC)—is one of the hardest, sharpest, and most versatile industrial materials in the world. From grinding wheels and blasting media to ceramic sintering, semiconductor substrates, and optical polishing, SiC continues to be one of the most important engineered abrasives and advanced ceramic materials of the modern manufacturing industry.
In this guide, you will learn everything about Carborundum: what it is, how it is made, technical properties, its industrial applications, the difference between black and green SiC, how grit sizes are classified, and how to choose the right grade for your process.
1. What Is Carborundum?
Carborundum is the trade name for Silicon Carbide (SiC), a compound of silicon and carbon created through high-temperature reaction inside an Acheson furnace. First discovered in 1891 by Edward Acheson, SiC quickly became one of the most widely used industrial abrasives due to its hardness, thermal stability, and sharp angular crystal structure.
Today, the term “Carborundum” is still used globally, especially in India, Southeast Asia, Africa, and Middle East markets. In technical and industrial sectors, the material is universally referred to as Silicon Carbide.
1.1 Chemical Composition
- Molecular formula: SiC
- Crystal structure: Hexagonal (α-SiC) or cubic (β-SiC)
- Hardness: Mohs 9.2–9.4 (one step below diamond)
- Melting point: > 2700°C (sublimes instead of melting)
- Thermal conductivity: High, comparable to metals
- Electrical property: Semiconductor (used in high-voltage electronics)
The combination of extreme hardness, thermal resistance, and chemical stability makes Carborundum ideal for high-performance grinding, polishing, refractory, and engineering applications.
2. How Is Carborundum (SiC) Produced?
Carborundum is produced through the Acheson process, where silica sand and carbon (usually petroleum coke) react at temperatures above 2000°C. A typical production process includes:
2.1 Raw Material Selection
- Quartz/silica sand as the silicon source
- Petroleum coke or anthracite as the carbon source
- Sawdust to create porosity
- Graphite core to conduct electricity
2.2 High-Temperature Synthesis
Inside the Acheson furnace, the mixture is heated electrically. The chemical reaction:
SiO₂ + 3C → SiC + 2CO↑
After 24–48 hours of controlled heating and cooling, a solid block of Silicon Carbide is formed. This block is then crushed, milled, graded, processed into grains, powders, and micro-powders.
2.3 Screening & Classification
The processed SiC is separated according to international standards:
- FEPA F12–F220 (macro grits)
- F230–F1200 (micro grits)
- JIS #240–#8000 (for ultra-fine polishing)
- Custom D10/D50/D90 micron sizes
3. Types of Carborundum: Black vs Green SiC
3.1 Black Silicon Carbide (Black SiC)
This is the most widely used form of Carborundum. It has sharp edges, good toughness, and is suitable for:
- Abrasive blasting
- Grinding wheels and coated abrasives
- Refractory raw materials
- Slip-resistant flooring
- Lapping and polishing
Purity: 97–99% SiC
3.2 Green Silicon Carbide (Green SiC)
Green Carborundum has a more brittle crystal structure and higher purity. It is used for:
- Precision polishing (optics, sapphire, glass)
- Advanced ceramic sintering
- Semiconductor and wafer lapping
- Hard alloy grinding
Purity: ≥ 99% SiC
3.3 Key Differences
- Black SiC: Tougher, more economical, industrial applications
- Green SiC: Harder, sharper, high-precision operations
4. Physical & Mechanical Properties of Carborundum
Carborundum is used widely because it offers an outstanding combination of properties:
4.1 Hardness
At Mohs 9.2–9.4, it is harder than:
- Aluminum oxide
- Tungsten carbide
- Quartz
Only diamond and cubic boron nitride are harder.
4.2 Thermal Conductivity
SiC dissipates heat efficiently, making it ideal for:
- Grinding wheels running at high speed
- Hot-zone kiln equipment
- Semiconductor power modules
4.3 Chemical Inertness
Carborundum resists oxidation, acids, and alkalis, making it reliable in severe environments.
4.4 Electrical Characteristics
Certain grades of SiC are used as semiconductors in:
- Electric vehicles (EV)
- High-voltage inverters
- Solar inverters
- 5G base stations
5. Applications of Carborundum
Thanks to its exceptional properties, Carborundum is used in multiple sectors:
5.1 Abrasives
- Grinding wheels
- Abrasive papers & belts
- Blasting media
- Polishing compounds
- Lapping powders
5.2 Refractories
- Kiln furniture
- Burner nozzles
- Crucibles
- Castables
5.3 Metallurgy
- Deoxidizer
- Carburizer
- Special alloy production
5.4 Ceramics & Engineering
- Mechanical seals
- Wear-resistant components
- Armor plates
5.5 Electronics (Advanced SiC)
- SiC wafers
- Power semiconductors
- EV inverters
6. How Carborundum Grit Sizes Are Classified
6.1 FEPA Standard (Europe)
F12–F220 (macro), F230–F1200 (micro)
6.2 JIS Standard (Japan)
#240–#8000, used for ultra-fine polishing
6.3 Micron Powder (D50 or Full PSD)
Used in:
- Optical polishing
- Semiconductor processing
- Technical ceramics
7. How to Choose the Right Carborundum Grade
7.1 By Application
- Grinding & Sanding: Black SiC F24–F220
- Polishing: Black/Green SiC F320–F1200
- Optics/Glass: Green SiC micron powder
- Refractories: Black SiC lumps & granular
- Sintering: Green SiC fine powders
7.2 By Purity
- 97–99% SiC: Blasting, grinding
- ≥99% SiC: Polishing, ceramics, semiconductors
7.3 By PSD (Particle Size Distribution)
Tight PSD improves:
- Surface finish
- Cutting efficiency
- Process stability
8. FAQs About Carborundum
Is Carborundum the same as Silicon Carbide?
Yes. “Carborundum” is the old trade name for Silicon Carbide (SiC).
Is Carborundum safe?
Yes, when used properly with dust control and PPE. SiC is chemically stable and non-toxic.
Why is Carborundum used in grinding?
Because of its hardness, sharp edges, and ability to withstand high temperatures.
What is the difference between Carborundum and Aluminum Oxide?
- SiC is harder and sharper
- Aluminum oxide is tougher and longer-lasting in some applications
Conclusion
Carborundum (Silicon Carbide) is one of the most important industrial materials of the 21st century. Whether it is used for grinding wheels, blasting media, ceramic components, or semiconductor wafers, SiC delivers unmatched hardness, stability, and performance.
Understanding its properties and choosing the correct grade is essential for maximizing efficiency, product quality, and production cost control. If you are sourcing SiC, always evaluate purity, grit consistency, PSD distribution, and supplier capability.
